When a long glass capillary tube of radius 0.015 cm is dipped in a liquid, the liquid rises to a height of 15 cm within it. If the contact angle between the liquid and glass to close to 0°, the surface tension of the liquid, in milliNewton m -1, is [ρ( text liquid )=900 kgm -3, g =10 ms -2] (Give answer in closest integer).

Question

When a long glass capillary tube of radius 0.015 cm is dipped in a liquid, the liquid rises to a height of 15 cm within it. If the contact angle between the liquid and glass to close to 0°, the surface tension of the liquid, in milliNewton m -1, is [ρ( text liquid )=900 kgm -3, g =10 ms -2] (Give answer in closest integer). (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

Capillary rise h =(2 S cos θ/ρ gr ) S =(ρ grh /2 cos θ) =((900)(10)(15 × 10-5)(15 × 10-2)/2) S =1012.5 × 10-4 S =101.25 × 10-3=101.25 mN / m In question closest integer is asked so closest integer =101.00 Ans.

Capillary rise h=ρgr2Scosθ​ S=2cosθρgrh​ =2(900)(10)(15×10−5)(15×10−2)​ S=1012.5×10−4 S=101.25×10−3=101.25mN/m In question closest integer is asked so closest integer =101.00 Ans.